This is an easy question but I can't find good documentation. 

After installing  or "sourcing" biocLite and installed relevant packages (edgeR, etc) I can run my analyses. But after closing the R session, and then restarting it, I have to resource BiocLite and then load all packages again. Seems like I wouldnt want to do this each time. Is there an appropriate way to have my packages saved from previous installations, so i can just load (e.g.  > library(xxx) ) all neccessary BiocLite packages ? 

Thanks

I think you misunderstand the process. Once you have installed a package, it is available on a permanent basis. In other words, you should be able to just start R and then use library(edgeR), without having to reinstall the package.